Liquid disseminator



Sept. 6, 1966 L. M BUCHANAN LIQUID DISSEMINATOR Filed March 11, 1964 INVENTOR. Lee M. Buchanan United States Patent 3,271,103 LIQUID DISSEMINATOR Lee M. Buchanan, Frederick, Md., assignor to the United States of America as represented by the Secretary of the Army Filed Mar. 11, 1964, Ser. No. 351,260 1 Claim. (Cl. 2192) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment to me of any royalty thereon.

This invention relates to a process and apparatus for vaporizing liquids.

More specifically, the invention relates to a process and apparatus for vaporizing liquid disinfectants to effect sterilization of areas contaminated with various microorganisms.

Gaseous disinfection is a known and very effective way of killing micro-organisms. For example to decontaminate large enclosed areas gaseous disinfectants such as ethylene oxide, chlorine, sulfur dioxide, and formaldehyde have been used. However, in practice these materials present difficulties. Eethylene oxide is explosive, and so highly penetrating that it escapes from all but tightly sealed containers. Chlorine and sulfur dioxide are extremely corrosive. Formaldehyde tends to deposit as a solid polymer.

Recently, B-propiolactone (BPL) has been proposed as a suitable gaseous disinfectant. The vapor is nonflammable and noncorrosive. It vis, however, toxic to man, and great care must be exercised in its use. Furthermore, dissemination of BPL by commercial insecticide sprayers has proven unsatisfactory since most sprayers discharge the liquid into the air in the form of small droplets, which collect on surfaces before evaporating. Such contact is deleterious to various materials, such as various paints, and plastic surfaces.

It is one of the objects of this invention therefore, to provide a process and apparatus for vaporizing BPL.

It is another object of the invention to provide a process and apparatus for vaporizing any kind of liquid, especially liquid disinfectants, whereby a more efiicient use thereof is obtained, and damage to surfaces prevented.

Referring to the accompanying drawing, the vaporizer apparatus of this invention comprises a cylindrical container carrying a cap 11. The cap is provided with a centrally disposed flue 12. The bottom-of the container forms a reservoir portion which holds the liquid 13 to be vaporized.

For mechanically vaporizing the liquid, there is provided a centrifugal atomizer unit 14, located within container 10. The atomizer unit is comprised of an outer atomizer housing 15 and an inner motor housing 16, with air conduit 17 being formed therebetween. Within the motor housing is a motor 18. The motor has a hollow shaft 19, which forms a part of the liquid conveyance system. The top of the motor shaft carries two concentric rotable discs 20 and 21, which are concavely opposed to each other and meet at their peripheries to form a slit for improved atomization of the conveyed liquid.

The use of a centrifugal atomizer, rather than other types of atomizers, is an important feature of this invention. With this type of atomizer, more liquid surface per unit of volume is presented to the vaporizing air stream. Further, the rotating discs impart a mechanical atomization to the liquid that is not obtainable with other types of atomizers.

That portion of the hollow shaft within the confines of the two rotable discs has suitable radial bores 22 for discharging the liquid to be vaporized between the discs. Upon the opposite end of the hollow shaft is mounted a fan 23 suitable for effecting forced circulation of the atomizing air through the air conduit 17.

The motor 18 may be any conventional type, such as an electric :motor or an air motor. Access to the motor of either an electric power line or air line is provided by means of a suitable metal conduit (not shown) which protects the power line from the liquid in the reservoir.

A liquid conduit line 24 extends externally from near the bottom of the container to the hollow shaft of motor 18. The liquid conduit 24 is connected to hollow shaft 19 by conventional coupling means. This liquid conduit contains a valve 25 for adjusting the liquid flow rate, and may contain a suitable pump 26 for aiding the flow of liquid tothe atomizer. Ordinarily, however, the .atomizer itself exerts a suflicient pumping action.

There is provided in the liquid reservoir area of contahler 10 a suitable heating means 27 for heating the liquid to be vaporized. Heating the liquid effects a higher vapor pressure and, consequently, a greater propensity for vaporizing. The heating means is preferably an electric resistance heater, although any suitable heating means might be used.

Attached to the bottom of container is a base 28 containing air heater means 29. Air heater 29 is preferably an electric resistance heater, and heats the atomizing air drawn in from the ambient atmosphere through suitable openings (not shown) in base 28 by fan 29. Heating the atomizing air is an important feature of this invention, and provides for a greater amount of liquid being vaporized than would be otherwise possible.

Baflle means 30 is provided within the container between the atomizer and the flue to trap any unvaporized droplets and return them to the liquid reservoir.

In operation, a liquid such as BPL is introduced into the container 10, either through the top with cap 11 removed, or through a suitable opening in the container wall (not shown). A suitably calibrated sight glass 31 permits a ready determination of the amount of BPL in the reservoir. It should not, of course, completely cover the centrifugal atomizing unit. The amount of BPL introduced is correlated with the size of the area to be sterilized. Ordinarily, one gallon of BPL is sufiicient to decontaminate about 16,000 cubic feet of space.

The whole vaporizer unit may be placed within the area to be decontaminated and controlled by a master switch located outside the area. Alternatively, a duct (not shown) leading to the area to be decontaminated may be attached to flue 12.

The BPL is then heated by means of heater 27. The particular temperature to which the BPL is heated is not critical except that it should be lower than the boiling point (162 C.) since BPL may tend to decompose at this temperature. A thermostat 32 is employed to maintain the BPL at the selected temperature.

The atomizer unit is then activated. The discs are rotated at about 12,000 rpm. The operation of the motor activates fan 23 which draws air in through heater 29 and expels it through the small circular space surrounding the discs. The heated air is intermixed with the atomized and vaporized BPL and aids in further vaporization. Any unvaporized droplets are trapped by the walls of the container and by baflle 30, and returned to the liquid reservoir.

When the required amount of BPL has been vaporized, the unit is shut off, either manually or automatically.

While the foregoing description of the invention refers to BPL as the liquid vaporized, this is by way of example only and is not intended to limit the invention to this particular liquid. Other liquid disinfectants such as aqueous formaldehyde solution may be used. Water may also be vaporized to provide humidification.

I claim:

An apparatus for vaporizing liquid disinfectant comprising a cylindrical container; a cap on said container; a centrally disposed flue on said cap; a centrifugal atomizer unit within said container comprising a motor means located within a motor housing and having a hollow, vertically disposed, driven shaft, a pair of concentric, rotatable discs located at the upper end of 'said shaft, the said discs extending to be coterminous with the upper diameter of the motor housing, and the said discs being concavely opposed to each other and meeting at their peripheries to form a slit for improved atomization of the conveyed liquid, said shaft being provided with radial bores in that portion located between said discs, a fan attached to the lower end of said shaft and located below said motor housing, and an atomizer housing surrounding said motor housing and forming therewith a narrow air conduit; liquid heating means located in the lower portion of said container where the liquid to be vaporized is confined; a base on the bottom of said container for supporting the same; an air heater means located within said base; a liquid conduit extending from near the bottom of the container, external thereto, to said hollow shaft of said motor; battle means within said container and located between said centrifugal atomizer unit and said flue; and thermostat means for controlling the temperature of said liquid.

References Cited by the Examiner UNITED STATES PATENTS 2,176,174 10/1939 Gelakoski 26188 X 2,186,697 1/1940 Hildebrand 261142 2,523,371 9/1950 Jennings et a1 21-117 X 3,098,696 7/1963 Ballet a1 2158 X 3,192,167 6/1965 Ogawa et a1 239-223 X FOREIGN PATENTS 531,052 12/ 1940 Great Britain.

MORRIS O. WOLK, Primary Examiner.

F. W. BROWN, Assistant Examiner. 

